Bleach was the cause of a ‘major incident’ in which ten children had to be evacuated from a Winsford swimming pool earlier this year.
An investigation into what made children start coughing, complain of stinging eyes and, in some cases, even vomiting during a swimming lesson at Winsford Lifestyle Centre in March has concluded that sodium hypochlorite – known better as bleach when dissolved in water – was manually applied to the pool, creating harmful chloramines.
The report, carried out by Mike Dix, Cheshire West and Chester Council’s senior manager for culture and environment, found that the water in the pool’s balance tank, which maintains water and chlorine levels, was at a ‘low-low’ level, and the automatic disinfectant dosing system had been turned off.
Emergency services were called to the centre, which is run by Brio Leisure, just after 1.30pm on March 10, after a sudden pungent odour filled the air, causing irritation to the throat and eyes of staff and schoolchildren.
After some complained of stinging eyes and others began coughing and being sick, a major incident was initiated because of concerns that gaseous chlorine could be present, and the building was evacuated with a number of children being sent to hospital for assessment, although none required treatment.
In the report, Mr Dix wrote: “In order to restore the levels of free chlorine in the main pool the duty supervisor added sodium hypochlorite into the poolside overspill channel following Brio’s policies and procedure.
“Adding sodium hypochlorite to the relatively higher concentration of nitrogenous matter in the balance tank via the overspill channel could create relatively high levels of chloramines in the balance tank.
“The presence of the strong smell and the symptoms presented by the children and adults in the pool hall after using sodium hypochlorite in the overspill channel is, however, consistent with the production of chloramines which are known to cause respiratory and eye irritation and nausea at high levels.”
The sodium hypochlorite was added in accordance with Brio’s current policies and procedures on hand-dosing, which is ‘standard practice’ when free chlorine levels in the pool are low, the report said.
No overall breach in Brio's policies
There was no overall breach of Brio’s policies and procedures, although Mr Dix recommended they review them to ensure they reflect the fact that it is now known that high levels of cholramines can be created under certain circumstances which could result in discomfort for customers and staff.
When regulatory services visited Winsford Lifestyle Centre the day after the incident, they found that all storage of chemicals was satisfactory and in line with the data safety sheet recommendations.
Training records for all staff present in the pool hall on the day of the incident were up to date and no other chemicals were used at the poolside on the day.